128509331 has 4 divisors (see below), whose sum is σ = 135273000. Its totient is φ = 121745664.

The previous prime is 128509321. The next prime is 128509343. The reversal of 128509331 is 133905821.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 128509331 - 2¹⁰ = 128508307 is a prime.

It is a super-2 number, since 2×128509331² = 33029296308135122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128509321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3381806 + ... + 3381843.

It is an arithmetic number, because the mean of its divisors is an integer number (33818250).

Almost surely, 2^128509331 is an apocalyptic number.

128509331 is a deficient number, since it is larger than the sum of its proper divisors (6763669).

128509331 is an equidigital number, since it uses as much as digits as its factorization.

128509331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6763668.

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 128509331 is about 11336.1956140497. The cubic root of 128509331 is about 504.6359903358.

The spelling of 128509331 in words is "one hundred twenty-eight million, five hundred nine thousand, three hundred thirty-one".